1. Technical Field
The present disclosure relates to an optical waveguide, an optical module and a method of manufacturing the optical waveguide.
2. Related Art
In recent years, while maintenance of communication lines of a mission-critical system through an optical fiber communication technology is progressing steadily, there is an issue of electrical wiring within an information terminal still being a bottleneck. Therefore, in place of using an electric circuit board, which is carried out in every signal transmission using an electric signal, a photoelectric composite board (optical module) of a type, in which a high-speed portion is transmitted by an optical signal, is proposed in order to compensate for the limitations of the electric signal transmission speed.
In the photoelectric composite board, the optical signal is transmitted by an optical waveguide having a structure in which a core layer is surrounded by a cladding layer. For example, Patent Document 1 discloses an optical waveguide having a multilayer structure in which a plurality of core layers are provided.
In such an optical waveguide, first, a first cladding layer and a first core layer are sequentially formed on a board, and a plurality of core portions of a first layer are formed by exposing and developing the first core layer. Next, a second cladding layer for covering the core portions of the first layer and the first cladding layer is formed. Subsequently, a second core layer is formed on the second cladding layer, and a plurality of core portions of a second layer are formed by exposing and developing the second core layer. Subsequently, a third cladding layer is formed on the core portions of the second layer and the second cladding layer. Thereafter, the same processes as above are repeated, thereby forming the optical waveguide having the multilayer structure.